This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A177175 #5 Jan 20 2014 22:19:36 %S A177175 1,6,13,64,287,1515,8143,46030,265909,1572193,9443997,57529101, %T A177175 354394057,2204333079,13823770729,87311462772,554904606279, %U A177175 3546103422655,22772157825695,146876986425311,951065019090195 %N A177175 Sequence defined by the recurrence formula a(n+1)=sum(a(p)*a(n-p)+k,p=0..n)+l for n>=1, with here a(0)=1, a(1)=6, k=1 and l=-1. %F A177175 G.f f: f(z)=(1-sqrt(1-4*z*(a(0)-z*a(0)^2+z*a(1)+(k+l)*z^2/(1-z)+k*z^2/(1-z)^2)))/(2*z) (k=1, l=-1). %F A177175 Conjecture: (n+1)*a(n) +(2-7*n)*a(n-1) +(19-5*n)*a(n-2) +(43*n-134)*a(n-3) +4*(53-13*n)*a(n-4) +20*(n-5)*a(n-5)=0. - _R. J. Mathar_, Jul 24 2012 %e A177175 a(2)=2*1*6+2-1=13. a(3)=2*1*13+36+2+1-1=64. %p A177175 l:=-1: : k := 1 : m:=6:d(0):=1:d(1):=m: for n from 1 to 30 do d(n+1):=sum(d(p)*d(n-p)+k, p=0..n)+l:od : %p A177175 taylor((1-sqrt(1-4*z*(d(0)-z*d(0)^2+z*m+(k+l)*z^2/(1-z)+k*z^2/(1-z)^2)))/(2*z), z=0, 30); seq(d(n), n=0..30); %Y A177175 Cf. A176832. %K A177175 easy,nonn %O A177175 0,2 %A A177175 _Richard Choulet_, May 04 2010